Tube of uniform depth and variable width



Oct. 1, 1963 i J. E. DALGLEISH 3,105,522

TUBE OF UNIFORM DEPTH AND VARIABLE WIDTH Original Filed Dec. 10, 1956lllllzg- Q by:

W Tm Q 6 IN V EN TOR.

JOl/A/ 5. 24464 6/519 United States Patent 3,105,522 TUBE {PF UNIFQRMDEPTH ANE) VARIABLE WEDTH .iohn E. Dalgieish, East Detroit, Mich,assignor to Robert C. Veit, doing business as Veet industries, EastDetroit, Mich.

Griginai application Dec. 10, 1956, Ser. No. 627,215, new Patent No.2,976,679, dated Mar. 28, 1961. Divided and this application Apr. 15,1959, Ser. No. 896,553

3 (Jlfirns. (Ci. 138115) This invention relates to rocket combustionchambers and more particularly to tube construction which is part of theassembly that forms the chamber walls.

This application is a division of my co-pendmg application for tubularrocket combustion chamber Serial No. 627,215, filed December 10, 1956,now Patent No. 2,976,679.

One of the objects of this invention is to provide a tubular walledrocket combustion chamber having improved durability and reduced weight.

Another object of this invention is to provide a tubular walled rocketcombustion chamber in which the wall structure has sufiicient strengthto retain the required fuel under high pressure for cooling the hot wallof the combustion chamber.

A still further object of the invention is to provide tubular units forassembling into a tubular walled rocket combustion chamber, the tubularunits being individually fabricated in a manner which reduces cost andweight, while increasing the bursting strength thereof.

A still further object of the invention is to provide a tubular unit forassembly into a tubular walled rocket combustion chamber which isfabricated from flat sheet structure to obtain a reduced widthconforming to the reduced section of the rocket combustion chamber.

Another important object of the invention i to provide a tubular unitfor assembly into a tubular walled rocket combustion chamber wherein thecross-sectional area of the tubular unit is at a minimum at the reducedsection of the combustion chamber to provide increased flow velocity andenhanced cooling effect in that area of the combustion chamber.

Tubular walled rocket combustion chambers have been fabricated bybundling sufficient tubes in side-by-side relationship to form a hollowwall. The tubes are utilized to conduct the rocket fuel, which operatesas a coolant for the portion of the tube which is exposed to the heat ofcombustion within the rocket. The conventional rocket combustion chamberhas a throat section intermediate the ends thereof which has aconsiderably reduced circumference When compared to the end sections. Inorder that the tubes can be assembled in abutting relation throughouttheir lengths, it is necessary to reduce the width thereof at theintermediate portion which is located at the throat section of therocket chamber. In order to achieve this tube shape, tubes of uniformcross-section have been deformed in dies to produce an elongatedcrosssection in the direction of the circumference at the ends, and anelongated cross-section in a radial direction at the throat section ofthe chamber. This represents a complicated and expensive formingoperation requiring several steps to accomplish. Further, a smallportion of the tube area is wetted by the coolant at the throat sectionwhere Patented Get. 1, 1963 the most intense heat is developed and theburn-outs usually occur.

The structure which performs the preferred embodiment of my inventionutilizes a tube which is fabricated into the desired shape from flatstock. A pair of channel shaped members having varying depth of thechannel along the length thereof are first formed. These channel membersare then placed in abutting relationship with the open sides confrontingeach other. A thin web of similar material is placed between thechannels and a weld is made which joins the channels and the web whilesealing the joint throughout the length of the channel members. When thewelding is completed, a tandem tube, having uniform height and varyingwidth as required to fill a segment of the circumference of thecombustion chamber after assembly, is produced. The web strengthens theflat walls of the tube against the bending when high internal pressuresare developed therein by operating as a tension member between the flatwalls of the tube.

By fabricating the tube in the manner set forth, the cross-sectionalarea of the flow path of the coolant is considerably reduced in theregion subjected to maximum heating effects. The coolant therefore flowsover the hot wall at higher velocities than has been previouslyobtainable with the result that the thickness of the boundary layer isreduced and the heat transfer rate considerably improved. Prolongedoperation of the rocket is made possible by this feature, and theover-all durability is considerably enhanced.

The provision of the web not only increases the strength factor forresisting bursting when internal pressures are applied within the tube,but by the expedient of removing a short section of the Web at one endof the tube and enclosing the tube beyond the end of the web of aU-shaped passage through the tube is obtained for regenerative coolingwithout making necessary the provision of additional manifolding. Boththe weight and safety factors are improved since the extra piping andjoints are eliminated.

Accordingly, one of the principal objects of this invention is toprovide a fabrication process for forming a tubular walled rocketcombustion chamber which simplifies the operations required to obtain afinished tube of the desired configuration, and improves the strength,durability, and safety factors of the finished structure.

Other objects and advantages more or less ancillary to the foregoing,and the manner in which all the various objects are realized, willappear in the following description, which considered in connection withthe accompanying drawings, sets forth the preferred embodiment of theinvention.

In the drawings:

FIG. 1 is an assembly view of a rocket combustion chamber utilizing thepreferred embodiment of my invention;

FIG. 2 is a cross-sectional view taken along line 22 of FIG. 1;

FIG. 3 is a plan view of one of the parts of the tube prior to assembly;

FIG. 4 is an end View of the tube parts prior to assembly by welding;

FIG. 5 is a plan view of the assembly tube;

FIG. 6 is an end view of the tube shown in FIG. 5;

FIG. 7 is a side view of the assembled tube formed to the finishedshape; and

FIG. 8 is an end view of the tube shown in FIG. 7.

Referring first to FIG. 1, the preferred embodiment of my invention isshown therein as a rocket combustion chamber in assembled form. Aplurality of tubes 1% are assembled in side-by-side relationship to forman elongated double-walled tubular chamber. The internal pressureproduced by the combustion of the rocket fuels is restrained by aplurality of clamps i2 circumscribing the tubes 10 and maintaining thetubes 10 in the close sideby-side position. At one end of the tubularchamber an ejector 14 is provided for discharging fuel into thecombustion chamber. Details of the injector 14 are not shown and are nota part of this invention. A plurality of tension members 16 are joinedat one end to the clamps 12 and at the other end to the injector 14 tohold the injector 14 in place during the combustion process.

A tail nozzle 18 is located in the discharge end of the combustionchamber and is held in position by a series of tension members 20 whichare joined to the nozzle and the clamps 12. The fuel system (not shown)is connected to the injector 14 which introduces the fuel by sprayingthe same into the portion of the combustion chamber adjacent thereto.Combustion of the fuel is instantaneous and results in an extremely hightemperature gas which discharged through the throat section of thecombustion chamber and expanded in the discharge nozzle at supersonicvelocities at the nozzle 18.

Due to the high temperatures and turbulence within the chamber, adverseheating occurs at the combustion chamber wall which is sufiicient toburn the material thereof in a short time of operation, unless provisionis made to cool the Wall and transfer the heat away at a ratesufficient, to keep the wall from overheating. This is accomplished bythe tube construction which contains the fuel prior to its passagethrough the injector 14. For heat transfer reasons, the inner Wall orthe wall exposed to the high temperature of the rocket flame should beas thin as possible to construct. On the other hand, the high fuelpressures require adequate strength to prevent bursting of the tubes dueto the hydrostatic pressures in the tubes as the fuel is pumped into theinjector.

The preferred embodiment of my invention includes tube structure whichhas the thin wall required for adequate heat transfer and has highstrength characteristics for retaining the high hydrostatic pressuresfound in the fuel system. The tube 10 is a composite structurefabricated from weldable sheet metal having a thickness from .010 inchto 0.20 inch. A channel-shaped piece 22 is formed from the fiat stock,the width of the channel being the radial width of the tube in theassembled position, and the depth of the channel being approximatelyone-half the circumferential width of the tube 10 in the assembledposition.

Since the circumference of the combustion chamber is considerably lessin the throat section than at the injector or nozzle sections, thecircumferential width of the tube must be smaller proportionately if thetubes are to be assembled in uniform side-by-side position. The finishedshape of a single tube is best illustrated in FIG. 5.

In order to obtain the desired shape of the tube in the piece 22 isformed as shown in FIG. 3 by machining away a portion of the channelintermediate the ends thereof. The shape of the channel sides and theheight thereof is determined by the configuration of the combustionchamber. The height of the channel is approximately half the total widthof the tube it) throughout its length.

When the tube 10 is assembled a pair of channels 22 are disposed in aconfronting relationship as shown in FIG. 4 and a strip 24 of thinmaterial such as shim stock is placed therebetween. The strip 24 has aWidth slightly greater than the channel 22. The thickness of the strip24 is in a range of .005 to .010 of an inch as required to strengthenthe tube to Withstand pressure loads on the interior of the tube. Thechannels 22 are then brought into abutting relation with the strip 24and a weld 26 is made at the joint throughout the length of the tube.Weld 2:5 joins the channel sections and the strip 24 in one operation toobtain a unitary fluid-tight tandem tube structure. This welding is bestdone with the tube in a straight condition. However, after the wel inghas been finished the tube may then be formed to the eventual shape ofthe rocket combustion chamber wall.

The uniform depth of the tube facilitates the bending at the sectionwhere the tube has the least width. If the tube were formed from tubestock having uniform crosssection, maximum depth would occur at thepoint of least width and forming would be difiicult.

The cross-sectional area of the tube may be controlled by controllingthe depth of the channel 22. This makes it possible to obtain flowvelocity characteristics which are optimim for cooling at the point ofworst heat conditions.

Since the joints between the sides of the tubes, when assembled in acircular pattern, are radial in each instance, provision is made toobtain complementary surface engagement of the sides of the tube. Thisis accomplished by inclining the Web of the channel 22 at a smal anglein order that the inner Wall of the tube is slightly shorter than theouter Wall of the tube. This results in both the inner and outer wallsbeing smooth and without crevices which would appear if the side Wallswere parallel. The degree of angularity is a function of the diameter ofthe rocket combustion chamber and the number of tubes employed in theformation thereof.

In some operations it is desirable to utilize regenerative cooling whichinvolves carrying the fuel from one end of the combustion chamber to theother and return. By removing a short section or perforating the strip24 at one end of the tube and closing the tube over, a U- shaped channelextending throughout the entire length of the tube is formed. Theopening through the strip 24 provides the function of externalmanifolding required to establish a return passage in an adjacent tube.

Having thus described my invention, what I claim and desire to besecured by Letters Patent is:

l. A tube having a uniform depth and variable width throughout itslength for use in side-by-side relationship with other similar tubes forforming a double-curved hollow wall comprising a pair of confrontingchannel sections having a uniform depth throughout the length thereof,said channel sections having a variable width throughout the lengththereof, one side of said channel being wider at any transverse planethan the other side of the channel, and a relatively thin strip of metallying between said confronting channels, said strip having a thicknessapproximately half the thickness of the channel and being of uniformwidth, said strip being fused at the common engagement line between saidchannel and said strip to provide a fluid-tight joinder of theconfronting channels and said strip.

2. A tube having a uniform depth and variable width throughout itslength for use in side-by-side relationship with other similar tubes forforming a double-curved hollow wall comprising a pair of confrontingchannel sections having a uniform depth throughout the length thereof,said channel sections having a variable Width throughout the lengththereof, and a relatively thin strip of metal lying between saidconfronting channels, said strip having a thickness approximately halfthe thickness of the channel and being of uniform Width, the width ofsaid strip being greater than the depth of the channel for providing amargin extending beyond the sides of said channel, said strip beingfused at the common engagement line between said channel and said stripto provide a fluid-tight joinder of the confronting channels and saidstrip.

3. A tube having a uniform depth and variable width throughout itslength for use in side-by-side relationship References Cited in the fileof this patent With other similar tubes for forming a double-curved hol-UNITED STATES PATENTS low Wall comprising a pair of confronting channelsectiOns having a uniform depth throughout the length there- 388,824Sept. 4, 1833 of, said channel sections having a variable width through-5 1,500,456 Junie July 8, 1924 out the length thereof, one side of saidchannel being 17622564 MHHFIY et 22 Wider at any transverse plane thanthe other side of the 1,900,836 y 7, channel, and a relatively thinstrip of metal lying be- 1,935,659 Noack 21, 1933 tween said confrontingchannels, said strip having a thiek- 1,979,804 Lutz, 6, 1934 nessapproximately half the thickness of the channel and 10 2,216,227Chnstenson 1940 being of uniform Width, the width of said strip being2,794,319 Stockdale June 4, 9 greater than the depth of the channel forproviding a 2,830,577 Halford et -i- P 7, 1959 margin extending beyondthe sides of said channel, said 2,943,442 f July 5, 1960 strip beingfused at the common engagement line beggifs gl l gi i tween said channeland said strip to provide a fluid-tight 15 joinder of the confrontingchannels and said strip.

3. A TUBE HAVING A UNIFORM DEPTH AND VARIABLE WIDTH THROUGHOUT ITSLENGTH FOR USE IN SIDE-BY-SIDE RELATIONSHIP WITH OTHER SIMILAR FORFORMING A DOUBLE-CURVED HOLLOW WALL COMPRISING A PAIR OF CONFRONTINGCHANNEL SECTIONS HAVING A UNIFORM DEPTH THROUGHOUT THE LENGTH THEREOF,SAID CHANNEL SECTIONS HAVING A VARIABLE WIDTH THROUGHOUT THE LENGTHTHEREOF, ONE SIDE OF SAID CHANNEL BEING WIDER AT ANY TRANSVERSE PLANETHAN THE OTEHR SIDE OF THE CHANNEL, AND A RELATIVELY THIN STRIP OF METALLYING BEBETWEEN SAID CONFRONTING CHANNELS, SAID STRIP HAVING A THICKNESSAPPROXIMATELY HALF THE THICKNESS OF THE CHANNEL AND BEING OF UNIFORMWIDTH, THE WIDTH OF SAID STRIP BEING GREATER THAN THE DEPTH OF THECHANNEL FOR PROVIDING A MARGIN EXTENDING BEYOND THE SIDES OF SAIDCHANNEL, SAID STRIP BEING FUSED AT THE COMMON ENGAGEMENT LINE BETWEENSAID CHANNEL AND SAID STRIP TO PROVIDE A FLUID-TIGHT JOINDER OF THECONFRONTING CHANNELS AND SAID STRIP.